1. Field
The present disclosure relates generally to aircraft and, in particular, to monitoring the flight of an aircraft. Still more practically, the present disclosure relates to a method and apparatus for providing awareness of the state of an aircraft during testing of the aircraft.
2. Background
When an aircraft is developed, testing is conducted as part of the development of the aircraft. Flight testing is completed to gather data about the performance of the aircraft during the flight of the aircraft. This data may be used to evaluate the aircraft. For example, the data may be used to validate the performance of a particular design for the aircraft.
Additionally, the data may be used to determine whether the aircraft flies as desired and provides a desired level of safety. The flight tests also may be used to certify an aircraft with respect to safety and performance requirements of a particular government entity.
During the flight test, the pilot manipulates controls to perform different maneuvers. The manipulation of controls may change the positioning of control surfaces for the aircraft. As the flight test progresses, the pilots may cause the control surfaces to move toward the limits of the control surfaces.
For example, the pilots may manipulate the controls to change the pitch of the aircraft. The change in pitch may become progressively more aggressive during the flight test or over different flight tests. This change in pitch may cause the control surfaces to reach a limit. When the limit is reached, the aircraft may not perform as desired or as expected.
Many currently used flight control systems have controls in the cockpit that are mechanically connected to control surfaces in the aircraft. These controls are often connected to the control surfaces by linkages, cables, and other mechanical components. With this type of flight control system, when a control in the cockpit is moved to a limit, the control surface also reaches a limit of movement. In this manner, the pilot is able to tell when a control surface has reached a limit as to how far the control surface can be manipulated. In other words, when a limit in a control surface is reached, the control corresponding to that particular control surface may no longer be manipulated.
In performing flight testing, it is often undesirable to reach the limit for moving the control surface during a maneuver early in the process of flight testing the aircraft. As a result, the pilot may be able to move a control surface toward the limit but avoid reaching the limit during testing and normal flight.
Testing of aircraft with flight control systems in the form of fly-by-wire systems may be more difficult than testing with mechanical control systems. A fly-by-wire control system replaces the manual flight control found with mechanical systems with an electronic interface.
Thus, when the pilot moves a control in the cockpit, this movement of the control is converted into signals transmitted over wires, optical fibers, or other types of communications links. These signals are interpreted by a computer in the aircraft as a commanded aircraft response. In turn, the computer generates signals that are sent to the flight control surfaces to effect the commanded aircraft response. These signals are sent to devices, such as actuators, associated with the flight control surfaces.
As a result, the pilots may not have a feel for the actual position of a flight control surface based on the position of the pilot control. Consequently, flight testing of an aircraft using a fly-by-wire control system may be more difficult when trying to avoid limits for flight control surfaces. Therefore, it would be desirable to have a method and apparatus that takes into account at least some of the issues discussed above, as well as other possible issues.